Thanks @stevenjose ! Tried reaching out to her, to no avail.
You can print an image of a signature stored in a Data Collection by first downloading it to your device. Then you can print it like any other image.
To download an image of the signature, open the Data Collection it is stored in, click the action menu (the three dots icon) next to the signature, and select Download.
Obtaining a printable version of a filled-in form is not currently supported as far as I know. However, once we add a Connect to Data panel to Signature Input (in plan for the current quarter) it could be achieved by building a page for site admins with the same form connected to a read-only dataset (connector). This will populate the form with the submitted data and let the user print it using the browser’s built-in printing functionality.
HTH